Gehenna

(Hebrew, g hard). The place of eternal torment. Strictly
speaking, it means simply the Valley of Hinnom (Ge-Hinnom),
where sacrifices to Moloch were offered and where refuso of all sorts
was subsequently cast, for the consumption of which fires were kept
constantly burning.

And made his grove
The pleasant valley of Hinnom, Tophet thence
And black Gehenna called, the type of hell.